The electron microscopy core will house all the instrumentation needed for the recording of high-resolution images and electron diffraction data. It will operate at two sites one at Brandeis and one at Harvard Medical School. The Brandeis part of the core will contain a 300 kV field- emission source, liquid He cooled electron microscope for the very highest resolution work and for thick specimens. It will also contain three 120 kV instruments, two with liquid N2 cryo stages. The Harvard part of the core will contain a 200 kV field emission source microscope and a 120 kV thermionic gun microscope, both with cryostages. This complement of microscopes will allow investigators and their collaborators at both institutions rapid access to routine microscopy for project development and complementary high-end instruments for high- resolution work. The core will be managed by Linda Melanson (Brandeis) and Yifan Cheng (Harvard Medical School)..